At present, an enterprise communication system generally provides an enterprise switchboard service and a conference service. When a conference system calls an external user to access a conference, it may call a terminal of the external user through a switchboard, and the calling number displayed on the terminal of the external user is the switchboard number of the enterprise. If the external user misses the call, when dialing the number of the missed call (that is, the switchboard number) subsequently, the external user usually hears a switchboard prompt tone “please dial the extension number”, or is provided with a voice self-service “please perform a self-service operation according to the prompt tone”, but cannot access the conference corresponding to the missed call. If a user needs to access the conference, the user further needs to find an access number of a conference system to which the conference belongs and a conference identifier of the conference, and access the conference using the access number and the conference identifier, which is low in efficiency.